VinMichael

Damn, I am sort of second guessing myself right now.

I am not sure if I made the right decision by skipping the rotating assembly balance part of the rebuild.

Here is where I am at now:
Pistons installed and rods resized with ARP bolts


Also my crank has been turned and polished
Olds005.jpg

I feel like I am taking a shortcut. Is it too late to get the rotating assembly balanced? Or should I let it slide?

I will be using this car on the street. However, I did not build a BBO to run errands lol. I want to have fun with this car, and know that it is capable of 1/4 mile passes.

What will I gain by having it balanced?

Oh yeah, I am planning on using the flex plate from a 350 and buying a new harmonic balancer.

ah64pilot

You can still have it balanced. Take your crank, rods / pistons, balancer, and flexplate with you. They will need all of it to properly balance it.

VinMichael

Right on, thanks. I thought metal was removed from the small end of the rod during a balance job, that's why I felt unsure. I will call some engine shops tomorrow about this.

ah64pilot

No, it's taken off the big end. You see that flat spot on the rod cap? That's where they'll take it off. The crank counterweights are where they take off material for it. Either by drilling into the weight or shaving a little off of the rounded edge of it...depending on how bad it is. They should also weigh all the pistons and get them close as well.

VinMichael

The big end. Right, I took pics earlier because I thought that they seemed to have material taken off already.

this one looked shaved


So you think they will be able to weigh the pistons despite already being on the rod? I used my digital scale to weigh them before they were pressed on the rod and they were in 2 grams of eachother.

jensenracing77

they will have to remove the pistons to do it right but that would be the only rework that would need done. i will likely never build another engine without getting it balanced. i was shocked at how much smoother it ran.

captjim

I agree, for $200 the difference is amazing. One thing, though, I can't tell from the pics, are the pistons pressed on? I REALLY don't like the idea of removing them then re-installing if they are pressed. I guess there is no way around it. One "shortcut" would be to take 1 apart, weigh the rod and piston, then use those values to balance the crank. Pistons should all be very close but stock rods can vary several grams.

11971four4two

The guy who balances my engines is really picky. To do things right he would press all the pistons off the rods. Then he would weight match all 8 pistons and weight match all 8 rods. For further accuracy he wanted the piston rings and rod bearings so he could weigh them too for setting bob weights. When the crankshaft was being balanced he wants the harmonic balancer and flex plate or flywheel (with clutch cover) and bolts to install these items as well

Going thru these steps costs a few dollars. Results are smooth running engines

Good luck with your build

cutlassefi

Wrong, it's taken off the big and small end.
You have 2 types of weight, rotating, and reciprocating. That's the reason they need to do both ends.
Some guys weigh the whole assembly (rod and piston together) then just take weight off the bottom of the rod because it's easier. You could actually be making it worse because you could potentially be making the end to end further off.

Take everything in. Have them recheck the pin bores in the pistons after they press them off, sometimes they distort. Shoot for .0006-.0007 pin clearence and .0015 or so press fit on the rods. If you end up having an issue there then just use the Mopar .984 pin. You can have the rods and pistons honed to that size and go from there. Plus that .984 pin is about 35-40 grams lighter than the .980 pin you have now. That's a good thing.

Good luck.

Run to Rund

If the pins were pressed, they will get scratches/scuffed on disassembly and each time you press off the pins, you scuff/wear the small end of the rod. Balancing must be done with everything disassembled to do it right. If your pistons are stock weight, at this point I'd leave it alone, particularly for a stock type build, being run at moderate rpm.

VinMichael

Thanks for the input. The smoother it runs the better IMO.
Unfortunately, yes, the pistons are pressed on. I weighed the pistons and they are close. I think the greatest difference was -/+ 4 grams between two pistons. The others were around -/+ 2 grams from eachother, average.

I have rod bearings and rings to give to the engine balancer if we he requires them. The only thing I do not have is a harmonic balancer. Thank you for your input.
What you said about the Mopar pin sounds like a great back up plan. I will definately keep this is mind

One differing opinion. Thank you for your input. The machinist who did this work for me said something similar. He said for a stock type rebuilds it is not necessary to get it balanced. But I believe I have begun to surpass the stock type rebuild category. I plan to install a roller cam and edelbrock heads.

VinMichael

I just spoke with a shop in San Francisco that will take the job. I will be heading there today. They quoted me $250 for the job, and the person I spoke with said they will hone the piston bores to size if necessary. Thanks again to everyone who responded.

VinMichael

So I brought my rotating assembly to the engine shop today. They ordered a harmonic balance and a new flex plate, so they will start the job after the parts arrive.

Now I am thinking if I should upgrade the rods. Would it be a wise to do so? Or is it unnecessary? These are the ones I am looking at:


They are priced around $450 at ebay.com

How much power can the stock rods handle? What are the benefits of an H- beam rod? They seem like they would be more rigid than the stock rods.

jensenracing77

if you are not building real big HP, i wouldn't spend the money on them.

Octania

I see 4 rods...

thought you were working on a V8 ?!

cutlassefi

What's your anticipated hp/tq level?

The Eagles offer full floating pins and are actually lighter as well as being stronger but you'll have to clearance the block a little.
If you're at 450hp or less then the stockers will work for you. Too bad you didn't go that route first, they're worth it if you're going from scratch.

Run to Rund

You can't use rods set up for floating pins unless thee pistons have snap ring grooves.

VinMichael

Lmao!

I am shooting for 450hp or less. But I would like to achieve 500 ft lbs of torque. I plan to achieve this by running Edelbrock heads, a roller cam, headers, and an HEI. @ around 9.5:1 compression.

I paid too much for the 455 core, $800, so I was trying to reuse as many parts as possible. But now, I am not even reusing the G heads, or the intake manifold.

If I could do it over again, I would buy just a block for $200 or less, instead of an $800 core, and a stroker kit which run at around $2000. Instead of buying forged pistons $530, and having the stock crank turned $150, and having the stock rods resized with ARP bolts and pistons pressed $160. Rod and Main bearings $150, and rings $80. All of these things which I bought for my stock 455 are included in a stroker kit. Add $450 for Eagle rods and I would be close to the $2000 stroker kit which come with Eagle rods.
Those are KB887's in the pic above. They have snap ring grooves and come with spiro-locks.

VinMichael

Update:
I got my rotating assembly back from the engine shop. It's balanced now. Everything went fine.